.flex
	ul 
		- for(var i = 1; i <= 5; i++)
			li=i
		.bar
View Compiled
.flex {
	width: 50vw;
	height: 80px;
	line-height: 80px;
	background-color: white;
	position: absolute;
	top: 50%;
	left: 50%;
	margin: -25px 0 0 -25vw;
	
	ul {
		display: flex;
		padding: 0;
		margin: 0;
		box-shadow: 0 10px 20px 0 rgba(black, 0.25);
		
		li {
			flex: 1;
			list-style: none;
			text-align: center;
			position: relative;
			font-size: 20px;
			font-weight: bold;
			transition: 0.5s ease;
			cursor: pointer;
			user-select: none;
			
			&:hover {
				background-color: rgba(white, 0.25);
				color: #f564a9;
				
				@for $i from 2 through 5 {
					&:nth-of-type(#{$i}) ~ .bar {
						left: $i * 20% - 20%;
					}
				}
			}
		}
		
		.bar {
			width: 20%;
			background-color: #f564a9;
			height: 5px;
			position: absolute;
			left: 0;
			bottom: 0;
			transition: 0.5s ease;
		}
	}
}

View Compiled

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